This invention relates generally to flashlights, and in particular, to a hand-held, focusable beam flashlight having an improved switching mechanism.
Flashlights of the type including a barrel portion and a head unit which is threaded onto the barrel portion are known in the art. Such flashlights are powered by two or more drycell batteries connected in series within the barrel portion. In conventional flashlights of this type, the barrel portion includes a tail cap at one end which must be removed in order to replace the batteries. The other end of the barrel portion includes a switching mechanism for making and breaking the electrical circuit from a battery terminal, through a lip on the barrel portion to the flashlight bulb.
The switching end of the barrel is threaded externally in order to mate with an internal thread in the head unit. A movable contact on the switching mechanism is brought into contact with or displaced from the lip in the switch end of the barrel.
The head unit includes a parabolic reflector which has a central opening through which the flashlight bulb may pass as the head is threaded onto the barrel. As the head unit is further threaded onto the barrel, the parabolic reflector butts up against and displaces the movable contact to break the electrical circuit between the battery terminal and the flashlight bulb. Rotation of the head in the opposite direction, i.e. unthreading of the head, causes the electrical circuit to be re-established by permitting the movable contact to re-contact the lip.
Conventional flashlights of this type have a number of inherent disadvantages. For example, the removable tail cap is required in order to install and replace batteries in the flashlight barrel, since the switching mechanism in such flashlights is not removable. Consequently, additional machining is required to fabricate such flashlights, thus increasing the fabrication cost. Also an additional seal is required at the tail cap in order to maintain watertightness of the flashlight.
The batteries in such flashlights are held in contact with the switching mechanism by a stiff coil spring located at the tail end of the flashlight. In order to break the electrical circuit, the force of this spring, which is substantial, must be overcome. Thus, a metal-to-metal thread is required in order to withstand the force necessary to overcome the spring. Also, the switching mechanisms associated with such flashlights inherently have a large amount of slack between the movable contact and the lip. Such an arrangement reduces the speed of circuit connection and disconnection. Furthermore, the switch assembly in the known flashlights is not easily removable for replacement if broken or damaged because it is retained by the lip formed in the switch end of the barrel.